Field of the Invention
The present invention relates to a semiconductor switching element and a method of manufacturing the same.
Description of the Background Art
In recent years, inverter circuits have been widely used for controlling home appliances, industrial electric power apparatuses and the like in view of energy conservation. In an inverter circuit, a power semiconductor device including a semiconductor switching element repeatedly turns ON and OFF voltage or current, thereby exerting power control. With a rated voltage of 300 V or greater, an insulated gate bipolar transistor (hereinafter abbreviated as the “IGBT”) is mainly employed as a semiconductor switching element for its characteristics.
Meanwhile, in relation to the IGBT, with a structure in which emitter regions and trench-type gate electrodes are evenly provided, the element may be short-circuited due to any malfunction. In this case, an enormous amount of current flows and affects the element. Accordingly, for example, Japanese Patent Application Laid-Open Nos, 2011-204803 and 2014-063961 each show a structure in which emitter regions and trench-type gate electrodes are partially omitted so as to suppress current in the event of short-circuiting of the element.
However, as described above, there has been a problem that, with the structure in which a charge storage layer capable of reducing ON resistance is provided to an entire structure in which a trench-type gate electrode is not provided at a portion with no emitter region, when the element is interrupted and voltage is applied, the charge storage layer fails to be depleted and breakdown voltage reduces.